XFS: Check for valid transaction headers in recovery

When we are about to add a new item to a transaction in recovery, we need to check that it is valid first. Currently we just assert that header magic number matches, but in production systems that is present and we add a corrupted transaction to the list to be processed. This results in a kernel oops later when processing the corrupted transaction.

Instead, if we detect a corrupted transaction, abort recovery and leave the user to clean up the mess that has occurred.

---
 fs/xfs/xfs_log_recover.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

index 0280a25..6d961fc 100644
@@ -1417,7 +1417,13 @@ xlog_recover_add_to_trans(
 		return 0;
 	item = trans->r_itemq;
 	if (item == NULL) {
-		ASSERT(*(uint *)dp == XFS_TRANS_HEADER_MAGIC);
+		/* we need to catch log corruptions here */
+		if (*(uint *)dp != XFS_TRANS_HEADER_MAGIC) {
+			xlog_warn("XFS: xlog_recover_add_to_trans: "
+				  "bad header magic number");
+			ASSERT(0);
+			return XFS_ERROR(EIO);
+		}
 		if (len == sizeof(xfs_trans_header_t))
 			xlog_recover_add_item(&trans->r_itemq);
 		memcpy(&trans->r_theader, dp, len); /* d, s, l */

1.5.6.5